Well, theres a saying widespread in the pilot commmunity that says "Runway behind you is Runway useless" Most of the time any GA pilot would use the entire lenght of the runway but in this case, with an airliner and a commuter airplane is unwise to reject a departure from intersection, if the conditions permit for it.
Mainly cause all are fitted with Laptops and Perfomance software in wich is pretty much staright forward to upload the re-calculated take off distance and obtain the new take off data, with the new V figures, quickly and just on the H/p.
Thats why theres an entry in the FMC on the departure page called "TO SHIFT".You key the new recalculated lenght on the entry and voila.., all the data re-calculated. Most commuter pilots will accept happily a shift take off.